So, I was looking into more detail on 7-segment LCD displays on Digi-Key. I’ve already looked here before to shop for a 7-segment LCD display to use with my Raspberry Pi Zero 3D scanner, but I was dismayed by the prices of the gear. Now that I’ve been through Digi-Key’s selection of LED displays and have also seen high prices on those, well I guess I am no longer as dismayed as I once aws. The trick that the Raspberry Pi Foundation uses to get the Raspberry Pi Zero’s price so low is manufacturing on an absolutely massive scale. Nonetheless, for the sake of larger system building, it is a relief that the Raspberry Pi Zero itself is only a $5 component in your larger system.
But, anwyas, on the subject of 7-segment LCD display control. Upon closer analysis of the 7-segment LCD displays on Digi-Key, some of them are not multiplexed displays like the LED displays are. Rather, there are two control pins for every LCD segment on the display, plus a few more pins for common ground and voltage. So if you do want to drive an LCD display the same way you’d drive a multiplexed LED display, you need to buy an LCD display controller chip and insert that into your system, or build your own out of a collection of chips. However, some LCD 7-segment displays are multiplexed, typically only the more complicated ones.
Also looking on Wikipedia, it confirmed this knowledge, albeit only in a very minor side note on the liquid crystal display article. Most of the article was about compute monitor LCDs.
20191129/https://en.wikipedia.org/wiki/Liquid-crystal_display
Also, along the way, I found the Wikipedia articles on those flat printed flexible black-and-white striped ribbon cables you sometimes see internal to electronics. The name of the game is “anisotropic conductive film” and “elastomeric connector.” “Zebra” is also a fitting word to describe these.
20191129/https://en.wikipedia.org/wiki/Anisotropic_conductive_film
20191129/https://en.wikipedia.org/wiki/Elastomeric_connector
The Wikipedia article also notes that PWM brightness control in LED-backlit displays can cause motion sickness and eye strain to some users. That is, the LED light output is flicked directly via the PWM control signal, rather than feeding that into a low-pass filter and using software compensation for the non-linear brightness curve of LEDs. The rationale, of course is it’s an easy way to get a good linear response control on the LED brightness. But, be careful when you use multiplexed LED display and PWM brightness modulation in your electronics projects, they may cause a lot of grief to some users later down the line if your project becomes more popular.
20191129/https://discussions.apple.com/thread/1677617
20191129/https://superuser.com/questions/149362/is-an-led-monitor-better-for-eyes-than-an-lcd-monitor